, Volume 91, Issue 1, pp 549–558 | Cite as

Lake Trehörningen restoration project. Changes in water quality after sediment dredging

  • Sven-Olof Ryding


An increased load of domestic wastewater to Lake Trehörningen induced oxygen-poor water conditions and the development of a reduced sulphide-rich sediment layer. Severely polluted, the lake did not recover, even after advanced wastewater treatment and sewage diversion. Restoration measures with suction dredging and macrophyte elimination were applied in 1975 and 1976. The loose topmost sediment was pumped into an embanked and overgrown bay which was used as a settling pond. The activities also included a restoration of the shorelines. This project is the largest restoration programme carried out in Sweden on a single lake, corresponding to a cost of about US $2 000 000.

The restoration of Lake Trehörningen was followed by a highly intensive research programme which included water chemistry and algal assays. The concentrations of phosphate and total phosphorus decreased by 73 and 50% respectively, as summer average values, two years after the restoration. However, the concentrations of phosphorus are still too high to permit this element to act as a prime algal growth-limiting nutrient. The algal biomass has also remained at the same magnitude as before the restoration. Nitrate-N concentrations showed a tenfold increase, based on average values for the summer period. However, based on the results of the algal assays, a rapid and marked response was obvious, with a drastic decline in the algal growth potential.

In addition, the water quality of the tributaries was frequently of an objectionable character (0.1–0.2 g P m−3). The nutrient loading from these sources exceeds the critical level for the lake, and measures have now been carried out to treat all the inflowing waters for the removal of phosphorus.


lake restoration sediment dredging nitrogen phosphorus algal assays 


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  1. Bengtsson, L., Fleischer, S., Lindmark, G. & Ripl, W., 1975. Lake Trummen restoration project. I. Water and sediment chemistry. Verh. Int. Verein. Limnol. 19: 1080–1087.Google Scholar
  2. Björk, S., 1972. Swedish lake restoration program gets results. Ambio 1: 153–165.Google Scholar
  3. Claesson, A. & Forsberg, Å., 1978. Algal assay procedure with one or five species. Minitest. Mitt. Int. Verein. Limnol. 21: 21–30.Google Scholar
  4. Claesson, A. & Ryding, S.-O., 1980. Characterization of the recovery processes in hypertrophic lakes in terms of actual (lake water)- and potential (algal assay) chlorophyll. In: Barica, J. & Mur, L. R. (Eds.) Hypertrophic Ecosystems, pp. 281–289. Developments in Hydrobiology, Vol. 2. Junk, The Hague.Google Scholar
  5. Cronberg, G., Gelin, C. & Larsson, K., 1975. Lake Trummen restoration project. II. Bacteria, phytoplankton and phytoplankton productivity. Verh. Int. Verein. Limnol. 19: 1088–1096.Google Scholar
  6. Dunkers, K. & Söbderlund, H., 1978. Sjörestaurering och dagvattenbehandling -nya metoder — nya aspekter. Väg- och vattenbyggaren 10: 31–32.Google Scholar
  7. Dunst, R. C., Born, S. M., Uttormark, P. D., Smith, S. A., Nichols, S. A., Peterson, J. O., Knauer, D. R., Serns, S. L., Winter, D. R. & Wirth, T. L., 1974. Lake rehabilitation techniques and experiences. Dept. Nat. Resour., Tech. Bull. No 75, Madison, Wisconsin. 179 pp.Google Scholar
  8. Orrje & Co, Skandiaconsult, 1973. Teknisk beskrivning över restaurcringen av sjbn Trehörningen. Orrje & Co, Skandiaconsult, 52.0011–08, 1973.01.18. 21 pp.Google Scholar
  9. Ryding, S.-O., 1978. Recovery of polluted lakes. Loading, water quality and responses to nutrient reduction. Acta Univ. Upsal., Abstracts of Uppsala dissertations, No. 459, 44 pp.Google Scholar
  10. Ryding, S.-O., 1980. Monitoring of inland waters. OECD eutrophication programme. The Nordic project. Scandinavian Council for Applied Research, Secretariat of Environmental Sciences, Publ. 1980: 2. 207 pp.Google Scholar
  11. Ryding, S.-O., 1981. Reversibility of man-induced eutrophication. Experiences of a lake recovery study in Sweden. Int. Revue ges. Hydrobiol. 66: 449–503.Google Scholar
  12. Ryding, S.-O. & Forsberg, C., 1977. Sediments as a nutrient source in shallow, polluted lakes. In: Golterman, H. L. (Ed.) Interactions between Sediments and Fresh Water, pp. 227–234. Junk, The Hague.Google Scholar
  13. Ryding, S.-O. & Forsberg, C., 1980a. Short-term load-response relationships in shallow, polluted lakes. In: Barica, J. & Mur, L. R., (Eds.) Hypertrophic Ecosystems, pp. 95–103. Developments in Hydrobiology, Vol. 2. Junk, The Hague.Google Scholar
  14. Ryding, S.-O. & Forsberg, C., 1980b. Hydrologi, ämnestrans-port och vattenkvalitet i Finjasjön 1976–1978. Hässleholms Kommun, Gatukontoret, April 1980. 41 pp.Google Scholar
  15. Vollenweider, R. A., 1968. Scientific fundamentals of the eutrophication of lakes and flowing waters with special reference to nitrogen and phosphorus as factors in eutrophication. OECD DASJCSI 68.27, Paris. 254 pp.Google Scholar
  16. Vollenweider, R. A., 1975. Input-output models with special reference to the phosphorus loading concept in limnology. Schweiz. Z. Hydrol. 37: 53–84.Google Scholar

Copyright information

© Dr W. Junk Publishers 1982

Authors and Affiliations

  • Sven-Olof Ryding
    • 1
  1. 1.National Swedish Environment Protection Board, Research DepartmentWater Quality LaboratoryUppsalaSweden

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